In the past, a disk portion of a wheel (disk wheel) of an automobile has been provided with a plurality of penetration portions penetrating the wheel for the purpose of reducing the weight and decorating the wheel, as well as for cooling a brake disposed inside the wheel.
However, in the case where an automobile is exported by means of sea transport for a long time, since the automobile wheel of the automobile is exposed to an atmosphere containing salt and moisture, the salt and moisture penetrate the automobile wheel of the automobile via the penetration portions, thereby causing a problem in that rust is caused in a rotor of a disk brake disposed inside the wheel.
In order to suppress such a problem, there is known a rustproof cover which is provided on a surface portion (outside) of the disk portion of the wheel so as to temporarily shield the penetration portions (for example, see Patent Document 1 and Patent Document 2).
It is desirable that the rustproof cover may be formed of a thin resin. The rustproof cover should not be easily separated from the wheel due to vibration or the like during transport, and should be easily separated from the wheel during a separation operation. In addition, since the rustproof cover is generally scrapped by a consignee, it is necessary to suppress an increase in the manufacture cost.
Patent Document 1 discloses a disk-shaped rustproof cover which is formed of a thin hard synthetic resin such as a hard vinyl chloride resin. The rustproof cover is provided with a plurality of radial and circular-arc ribs so as to improve the strength of the rustproof cover. In addition, a plurality of cap-shaped locking portions penetrating the rustproof cover is attached to the center portion of the rustproof cover, and the plurality of locking portions is fitted to a plurality of wheel nuts thereby attaching the rustproof cover to the disk portion of the wheel.
Patent Document 2 discloses a disk-shaped rustproof cover which is formed of a thin synthetic resin. The rustproof cover is elastically fitted to the inner periphery of each penetration portion by means of a matching operation with the outer periphery of the disk portion of the wheel or an individual matching operation thereof.